Gregorian leap day calendar was first used in 1582, meaning we have had 132.75 leap years in the past 531 years, and to account for slight differences between astronomical and calendar years 3 leap days are omitted every 400 years, this means that in total we have had 129.73 leap days in total- not 495.

You also can't just discard remainders and roots from the equation and keep them for later use.

Even assuming you got everything right down to the 8-5 is 3, the completely butchered leap year equation means that 8 - 3.0229 = 4.9771

Half Life 4.9771 Confirmed?
But why do I care I know this is just copypasta anyway